How to 3D Print Waterproof

Introduction

Many people have misunderstandings about the meaning of "waterproof". Basically, waterproofing and impermeable are different. Waterproof means that water cannot penetrate (and pass through) the component, while watertight means that water can neither enter nor escape from the component. In practice, if your print will be exposed to rain or humid climates, you'll probably want it to be waterproof. Whether it remains watertight or not is irrelevant. For example, if you are 3D printing a car part (such as part of a bumper), there is no need to make it watertight, but it should be waterproof to ensure it remains intact despite repeated exposure to rain. On the other hand, if you are printing a water bottle, it should be  watertight to keep the liquid from escaping. In this article, it will focus on how to waterproof 3D printed parts, showing you a few different methods including material selection, slicer setup, post-processing and testing.

Material selection PLA, ABS, PETG and PP are good choices for waterproof prints

Some materials are more prone to chemical reactions and deformation than others, resulting in parts that are not waterproof. If a material reacts to water, then 3D prints made from that material are likely to deform when in contact with water or placed in a humid environment. Therefore, choosing materials should be your first consideration. However, this is not the only step. While some materials may be labeled waterproof, parts made from them may not be waterproof. If you are going to chooce FDM print, there are three main materials you might consider: PLA, ABS, and PETG. Although less common, polypropylene (PP) is also a material worth considering due to its waterproof properties. Let’s learn about them in detail.

Polylactic Acid (PLA): Not known to be the most waterproof material, but it does work. It works fine as long as it comes in contact with cold water rather than hot water.

ABS: is an excellent waterproof printing material. Components may crack and warp at low temperatures, but its waterproof properties are reported to last for a long time otherwise.

PETG: It is a modified material of PET (used in water bottles) and is an excellent material for making waterproof prints. PETG is generally considered waterproof and has excellent heat resistance. This material may be the best choice for printing waterproof parts, as long as you also incorporate other waterproofing technologies.

PP: One of the best choices for waterproof printing. It is inherently hydrophobic, retains moisture well, and has good chemical and impact resistance. If you plan to use 3D printed parts for anything that comes into contact with food or drink, you should use food safe materials such as PP or PETG, not ABS or ASA. Before printing, make sure the manufacturer of your specific filament states that it meets food safety standards. Heat Resistance Heat resistance does not have anything to do with the water resistance of a part, but depending on the intended application it may. For example, parts that are dishwasher safe are subject to extreme temperatures and large amounts of water, so material selection is particularly important. Be sure to choose materials that are heat-resistant and waterproof, such as ABS or PETG.

Slicing settings Adjusting the layer height can make the part more waterproof

One of the most important factors in 3D printing is the slicing method and settings. In addition, the settings determine how tight, full, and protected the 3D printed part is, which in turn affects its water resistance. It is important to note that while the setting of the slices plays an important role in the waterproofness of a 3D print, some models are more difficult to waterproof than others. Complex models with lots of detail are more challenging, so be sure to keep your model as simple as possible. Once the model has been adjusted accordingly, the print settings are ready to be used. Here are the most important settings to consider. Extrusion Purposefully overextending a print can make the part more water-resistant because it reduces the chance of gaps in the print. You can achieve this by increasing the extrusion rate (sometimes called the "flow rate") in the slicer. The printed layers bond better to each other, which can be achieved by increasing the temperature. Increasing the temperature can also help with over-squeezing. Nozzle Size While this is not a slicer setting per se, a wider nozzle helps make the part more waterproof. A wider nozzle means a thicker extrusion line, including the part’s outer shell.

Regardless of how many shells there are, a thicker shell means there is less chance of a shell accidentally being printed thin enough to create holes or gaps during the printing process. Of course, more housing will only help waterproof printing, with or without a thicker nozzle. Layer Height Using a lower layer height setting can improve the water resistance of your print because it creates denser layers that are more conducive to water resistance. Smaller layer heights also improve layer adhesion, so even if you spend a little more time printing, the final object is less prone to cracking and leaking.

Post-process coating is a great way to fill layer lines and prevent leaks

Post-processing is one of the best ways to make 3D printed parts waterproof. The layer smoothing treatment can produce a good waterproof effect. It blends layers, eliminates layer line gaps, and creates a tighter seal around the part. There are a few different methods of layer smoothing, but the main technique is to apply solvent to the soluble print. Some materials are soluble in certain chemicals. For example, ABS is partially soluble in acetone. Acetone: This is probably the most common solvent used for post-processing. The acetone vapor smoothing method is suitable for ABS, ASA, HIPS, PMMA and polycarbonate filaments. Epoxy: Another post-processing method is to apply epoxy to your print. Epoxy resin quickly smoothes out layer patterns on 3D printed parts, making the parts less susceptible to the effects of water. Wax: Although less common, wax is also a great help in waterproofing your prints. It won't dissolve the layer like acetone will. Instead, it fills the gaps between layers.

Test Now that you've created your waterproof component

Don’t immediately think that by following the above advice you will always have waterproof parts. Test printing can be a little tricky and may also depend on the geometry of the design. If the piece can hold a cup or so of water (whether that's the intended purpose or not), try filling it with water and marking exactly where the water line is. Be sure to keep the piece in a cool place and watch closely the next day to see if the water level drops significantly. If so, you have a leak. If your part does not contain water, place it on a scale and note the dry weight. Then, let the parts soak in a basin of water for a day. Dry the part surface thoroughly and weigh it again. If your parts are much heavier now than they were a day ago, water may have gotten into them.

Conclusion

While 3D printed parts have many advantages, they are generally not waterproof. Taking the time to waterproof your parts will make them last longer and protect them from water damage. If your part is not waterproof, we recommend revisiting the above advice: adjust microtome settings, apply a uniform epoxy seal or other post-processing method, or possibly use a different material entirely.